Subsurface bioimaging using angular domain optical backscattering illumination

While coherence or time domain optical tomography within highly scattering media observes the shortest path photons over the dominant randomly scattered background light, backscattering angular domain imaging employs micromachined collimators to detect photons within small angles of laser light reflected from the high scattering medium. These angular filters are composed of micromachined semicircular silicon collimator channels. By illuminating from the front side phantom test objects were observed in scattering media up to 3 mm deep in the medium at effective scattered to ballistic ratios from 1:1 to greater than 3E12:1. Results from carbon coating the collimators using a sputtering system to decrease internal reflectivity are shown.